I imagine there are many ways to say No to the question, but NO is the most direct one. If the vent pipes are PVC then you must have direct vent units.

: Could I vent a sewer vent into an existing vent for the gas furnace or hot water heater? The furnace and hot water heater each have a separate vent pipe above the roof. The exiting vent pipes are PVC. The house is a one story. Thanks for your advice. Jerry